So, there's a short section in a wonderful and insightful documentary called Flight from Death that illustrates one way to look at this problem.

I'm scanning it right now to find the exact quote and will edit it when I find it, but it can be paraphrased as such:

"Social death" can be thought of as just as profound and physical death. To avoid social death, humans must find value in society - but a given society only provides certain avenues for value. For example, in some societies, the highest form of value one can find is in the ability to impale a fish with a sharp stick, while in other societies the ability to toss a rubber ball through a metal hoop will confer great wealth and success.

If society doesn't provide an appropriate avenue for some people to find social value, they experience a "social death." These people are overwhelming homeless, addicted, etc.

This is just one way to think about it, but I don't think it's mutually exclusive with any other major way to think about it.